/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.realm;

import org.apache.catalina.*;
import org.apache.tomcat.util.ExceptionUtils;

import javax.naming.Context;
import java.security.Principal;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * <p>Implementation of {@link org.apache.catalina.Realm} that is based on an implementation of
 * {@link UserDatabase} made available through the global JNDI resources
 * configured for this instance of Catalina.  Set the <code>resourceName</code>
 * parameter to the global JNDI resources name for the configured instance
 * of <code>UserDatabase</code> that we should consult.</p>
 *
 * @author Craig R. McClanahan
 * @since 4.1
 */
public class UserDatabaseRealm
		extends RealmBase {


	// ----------------------------------------------------- Instance Variables

	/**
	 * Descriptive information about this Realm implementation.
	 */
	protected static final String info =
			"org.apache.catalina.realm.UserDatabaseRealm/1.0";
	/**
	 * Descriptive information about this Realm implementation.
	 */
	protected static final String name = "UserDatabaseRealm";
	/**
	 * The <code>UserDatabase</code> we will use to authenticate users
	 * and identify associated roles.
	 */
	protected UserDatabase database = null;
	/**
	 * The global JNDI name of the <code>UserDatabase</code> resource
	 * we will be utilizing.
	 */
	protected String resourceName = "UserDatabase";


	// ------------------------------------------------------------- Properties

	/**
	 * Return descriptive information about this Realm implementation and
	 * the corresponding version number, in the format
	 * <code>&lt;description&gt;/&lt;version&gt;</code>.
	 */
	@Override
	public String getInfo() {

		return info;

	}

	/**
	 * Return the global JNDI name of the <code>UserDatabase</code> resource
	 * we will be using.
	 */
	public String getResourceName() {

		return resourceName;

	}

	/**
	 * Set the global JNDI name of the <code>UserDatabase</code> resource
	 * we will be using.
	 *
	 * @param resourceName The new global JNDI name
	 */
	public void setResourceName(String resourceName) {

		this.resourceName = resourceName;

	}


	// --------------------------------------------------------- Public Methods

	/**
	 * Return <code>true</code> if the specified Principal has the specified
	 * security role, within the context of this Realm; otherwise return
	 * <code>false</code>. This implementation returns <code>true</code>
	 * if the <code>User</code> has the role, or if any <code>Group</code>
	 * that the <code>User</code> is a member of has the role.
	 *
	 * @param principal Principal for whom the role is to be checked
	 * @param role      Security role to be checked
	 */
	@Override
	public boolean hasRole(Wrapper wrapper, Principal principal, String role) {
		// Check for a role alias defined in a <security-role-ref> element
		if (wrapper != null) {
			String realRole = wrapper.findSecurityReference(role);
			if (realRole != null)
				role = realRole;
		}
		if (principal instanceof GenericPrincipal) {
			GenericPrincipal gp = (GenericPrincipal) principal;
			if (gp.getUserPrincipal() instanceof User) {
				principal = gp.getUserPrincipal();
			}
		}
		if (!(principal instanceof User)) {
			//Play nice with SSO and mixed Realms
			return super.hasRole(null, principal, role);
		}
		if ("*".equals(role)) {
			return true;
		} else if (role == null) {
			return false;
		}
		User user = (User) principal;
		Role dbrole = database.findRole(role);
		if (dbrole == null) {
			return false;
		}
		if (user.isInRole(dbrole)) {
			return true;
		}
		Iterator<Group> groups = user.getGroups();
		while (groups.hasNext()) {
			Group group = groups.next();
			if (group.isInRole(dbrole)) {
				return true;
			}
		}
		return false;
	}

	// ------------------------------------------------------ Protected Methods

	/**
	 * Return a short name for this Realm implementation.
	 */
	@Override
	protected String getName() {

		return (name);

	}

	/**
	 * Return the password associated with the given principal's user name.
	 */
	@Override
	protected String getPassword(String username) {

		User user = database.findUser(username);

		if (user == null) {
			return null;
		}

		return (user.getPassword());

	}

	/**
	 * Return the Principal associated with the given user name.
	 */
	@Override
	protected Principal getPrincipal(String username) {

		User user = database.findUser(username);
		if (user == null) {
			return null;
		}

		List<String> roles = new ArrayList<String>();
		Iterator<Role> uroles = user.getRoles();
		while (uroles.hasNext()) {
			Role role = uroles.next();
			roles.add(role.getName());
		}
		Iterator<Group> groups = user.getGroups();
		while (groups.hasNext()) {
			Group group = groups.next();
			uroles = group.getRoles();
			while (uroles.hasNext()) {
				Role role = uroles.next();
				roles.add(role.getName());
			}
		}
		return new GenericPrincipal(username, user.getPassword(), roles, user);
	}


	// ------------------------------------------------------ Lifecycle Methods

	/**
	 * Prepare for the beginning of active use of the public methods of this
	 * component and implement the requirements of
	 * {@link org.apache.catalina.util.LifecycleBase#startInternal()}.
	 *
	 * @throws LifecycleException if this component detects a fatal error
	 *                            that prevents this component from being used
	 */
	@Override
	protected void startInternal() throws LifecycleException {

		try {
			Context context = getServer().getGlobalNamingContext();
			database = (UserDatabase) context.lookup(resourceName);
		} catch (Throwable e) {
			ExceptionUtils.handleThrowable(e);
			containerLog.error(sm.getString("userDatabaseRealm.lookup",
					resourceName),
					e);
			database = null;
		}
		if (database == null) {
			throw new LifecycleException
					(sm.getString("userDatabaseRealm.noDatabase", resourceName));
		}

		super.startInternal();
	}

	/**
	 * Gracefully terminate the active use of the public methods of this
	 * component and implement the requirements of
	 * {@link org.apache.catalina.util.LifecycleBase#stopInternal()}.
	 *
	 * @throws LifecycleException if this component detects a fatal error
	 *                            that needs to be reported
	 */
	@Override
	protected void stopInternal() throws LifecycleException {

		// Perform normal superclass finalization
		super.stopInternal();

		// Release reference to our user database
		database = null;

	}
}
